Ever Wondered How the Internet Got Started?

History of the Internet

 

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How the Internet Came to Be

The Birth of the ARPANET

TMy involvement began when I was UCLA doing graduate work from 1967 to 1972. There were several people at UCLA at the time studying under Jerry Estrin, and among them was Stephen Crocker. Stephen was an old high school friend, and when he found out that I wanted to do graduate work in computer science, he invited me to interview at UCLA.

When I started graduate school, I was originally looking at multiprocessor hardware and software. Then a Request for Proposal came in from the Defense Advanced Research Projects Agency, DARPA.

The proposal was about packet switching, and it went along with the packet-switching network that DARPA was building.

Several UCLA faculty were interested in the RFP. Leonard Kleinrock had come to UCLA from MIT, and he brought with him his interest in that kind of communications environment. His thesis was titled Communication Networks: Stochastic Flow and Delay, and he was one of the earliest queuing theorists to examine what packet-switching networking might be like. As a result, the UCLA people proposed to DARPA to organize and run a Network Measurement Center for the ARPANET project.

This is how I wound up working at the Network Measurement Center on the implementation of a set of tools for observing the behavior of the fledgling ARPANET. The team included Stephen Crocker; Jon Postel, who has been the RFC editor from the beginning; Robert Braden, who was working at the UCLA computer center; Michael Wingfield, who built the first interface to the Internet for the Xerox Data System Sigma 7 computer, which had originally been the Scientific Data Systems (SDS) Sigma 7; and David Crocker, who became one of the central figures in electronic mail standards for the ARPANET and the Internet. Mike Wingfield built the BBN 1822 interface for the Sigma 7, running at 400 Kbps, which was pretty fast at the time.

Around Labor Day in 1969, BBN delivered an Interface Message Processor (IMP) to UCLA that was based on a Honeywell DDP 516, and when they turned it on, it just started running. It was hooked by 50 Kbps circuits to two other sites (SRI and UCSB) in the four-node network: UCLA, Stanford Research Institute (SRI), UC Santa Barbara (UCSB), and the University of Utah in Salt Lake City.

We used that network as our first target for studies of network congestion. It was shortly after that I met the person who had done a great deal of the architecture: Robert Kahn, who was at BBN, having gone there from MIT. Bob came out to UCLA to kick the tires of the system in the long haul environment, and we struck up a very productive collaboration. He would ask for software to do something, I would program it overnight, and we would do the tests.

One of the many interesting thing about the ARPANET packet switches is that they were heavily instrumented in software, and additional programs could be installed remotely from BBN for targeted data sampling. Just as you use trigger signals with oscilloscopes, the IMPs could trigger collection of data if you got into a certain state. You could mark packets and when they went through an IMP that was programmed appropriately, the data would go to the Network Measurement Center.

There were many times when we would crash the network trying to stress it, where it exhibited behavior that Bob Kahn had expected, but that others didn't think could happen. One such behavior was reassembly lock-up. Unless you were careful about how you allocated memory, you could have a bunch of partially assembled messages but no room left to reassemble them, in which case it locked up. People didn't believe it could happen statistically, but it did. There were a bunch of cases like that.

Continue to Page 2 of the History of the Internet.....

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